My favorite ground mount would be the Chopper, it's like the only thing that made me turn on WoW sounds after like ... 3 years of always-Winamp-in-background-no-WoW-Sounds policy?

The flying ones ... probably Rusted Drake at the momement since it matches my gear ( IRL friend who plays with me on the same realm just said ' RP ' but hey, if I got a choice between colors, why not pick the one that fits better! ), I'll let you judge it D:

Rusted:

Ironbound:

Back in TBC it'd be the Azure Netherdrake.

Surprised no Gnome fanatic said they love the Yogg25 0 Keepers mount though.

My all-time favorite ground mount would be the Black Qiraji Battletank. I don't have it but I enjoy gawking at the chick on my server who does when she is in Dal. As for flying nothing beats my Blue Proto-Drake